Data Object select method with retun type DataTable, Fields info is not picking automatically RSS

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  Irfan Ullah

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  51 Points

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  Data Object select method with retun type DataTable, Fields info is not picking automatically

  Jul 12, 2011 10:44 AM|LINK

  Hi,

  I have a DataObject class who have method GetCategory

  public List<Category> GetCategory()

  Im using this method with GridView and ListView its working fine, even Edit and Delete are also working fine

  To add AutoSorting functionality i added new method to class like below

  public DataTable GetTable()

  When i configure ObjectDataSource method for select operations GetTable(), GridView was unable to get fields information,

  Is there any method to add Category Object to DataTable as DataFields?? or how can i solve this problem. Please note that if i configure field information manually it still works fine.

  Thanks.

  • Edited by Irfan Ullah on Jul 12, 2011 10:45 AM
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  tompy_nation

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  Re: Data Object select method with retun type DataTable, Fields info is not picking automatically

  Jul 12, 2011 11:27 AM|LINK

  public static DataTable ToDataTable<T>(this IList<T> data)
      {
          PropertyDescriptorCollection properties =
              TypeDescriptor.GetProperties(typeof(T));
          DataTable table = new DataTable();
          foreach (PropertyDescriptor prop in properties)
              table.Columns.Add(
                  prop.Name,
                  (prop.PropertyType.IsGenericType && prop.PropertyType.GetGenericTypeDefinition() == typeof(Nullable<>))
                      ? Nullable.GetUnderlyingType(prop.PropertyType)
                      : prop.PropertyType
              );
          foreach (T item in data)
          {
              DataRow row = table.NewRow();
              foreach (PropertyDescriptor prop in properties)
                   row[prop.Name] = prop.GetValue(item) ?? DBNull.Value;
              table.Rows.Add(row);
          }
          return table;
      }

  Don't forget to click "Mark as Answer" on the post that helped you.
  • Marked as answer by Irfan Ullah on Mar 19, 2012 05:42 AM
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  Irfan Ullah

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  51 Points

  42 Posts

  Re: Data Object select method with retun type DataTable, Fields info is not picking automatically

  Jul 13, 2011 09:49 AM|LINK

  Thanks for reply,

  but what i exactly want is, on smart tag on GridView, when i choose datasource, GridView should refresh table schema,

  if retirm type of a method is Table or DataSet GridView could not get column information automatically. i want it to get column info at design time.

  thanks.

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  Decker Dong ...

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  Re: Data Object select method with retun type DataTable, Fields info is not picking automatically

  Jul 14, 2011 02:35 AM|LINK

  Irfan Ullah

  if retirm type of a method is Table or DataSet GridView could not get column information automatically. i want it to get column info at design time.

  Hello：）

  If you are using the Common DataTable, I'm afraid that's almost impossible because VS cannot execute dynamically your codes of creating a DataTable and map all the columns to the GridView.

  However, I think You can use Strongly-Typed DataTable (TableAdapter) instead.

  Thx

  • Edited by decker dong - msft on Jul 18, 2011 01:11 AM
  • Edited by decker dong - msft on Mar 19, 2012 05:48 AM
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  severn

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  Re: Data Object select method with retun type DataTable, Fields info is not picking automatically

  Mar 17, 2012 03:25 PM|LINK

  Hi there, did you use a table adapter as suggested after all?  I find that columns are not in the Selected Fields list for editing when the return type for my select method is a DataTable. 

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  Irfan Ullah

  Member

  51 Points

  42 Posts

  Re: Data Object select method with retun type DataTable, Fields info is not picking automatically

  Mar 19, 2012 05:43 AM|LINK

  please try tompy_nation's code it works fine, if you have any problem let me know in clear words what you want to do

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  severn

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  Re: Data Object select method with retun type DataTable, Fields info is not picking automatically

  Mar 19, 2012 01:17 PM|LINK

  Hi thank you for your reply. The link doesnt point to anything related to the subject? 

  I am using a gridview bound to an objectdatasource.  The select method returns a datatable of objects of type "Record".  If I use a datatable, the grid view will not list the columns for editing, so I had to create/add each bound field.  (This doesnt sound right)
  Firstly should I use a List for the select method instead of a datatable?
  
  I had my next problem when Updating.  The updatemethod expects a parameter of "Record", however when executing, it does not have values in it.  My SelectMethod is a stored procedure that returns multiple fields.  I expected that I could just add updateparameters manually in rowupdating allowing me to convert from string to datetime, string to decimal etc.  If I dont do this the string values from the grid will cause type errors.
  
  Is my approach incorrect?

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  Irfan Ullah

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  51 Points

  42 Posts

  Re: Data Object select method with retun type DataTable, Fields info is not picking automatically

  Mar 20, 2012 05:42 AM|LINK

  looks like you are mixing two different approaches,

  1) if you want to bind gridview with datatable, i would recomend to use sqlDataSource object, where u will have to add sql statements for select, delete and update, after setting query statements configure gridview, in presence of update, delete queries, gridview will itself understand to add editing fields,(editing templates) this method will allow you auto sort and much flexible but less secure

  2) if you are using strongly typed objects, like u define model class for products, DAL and BLL layers to access products table, then its recomended to use objectdatasource, here i would strongly recomend to add component model signature to all methods, for example

  [DataObjectMethod(DataObjectMethodType.Select,true)]
  public static IList<Product> GetAllProducts()
  {
     // your code here
  }

  above code is for select method, you need to add update and delete method in same way, this will help gridview to add editing controls, and delete functionality,

  about your second question, to update automatically in database, please ensure you have configured well datasource object as discussed above, ensure that controls are two way binded, Bind("ProductID") is two way. in binding options you can also select format for number and date time types

  hope this will help.